Principal Washington was actually previously shown in a filler, but he looked significantly different at the time. Check him out: Link

He originally had an eye patch and horrible scarring on his face, but I decided against that for several reasons. What’s ironic is that I boldly declared this at the time of that filler:

"The man with the eye patch might look a lot different in the end, but he'll still have that stylish eye patch and scarring."

Apparently, past me is a dirty rotten stinking liar, as those are the two main things I wound up taking away from his design! Curse past me and his wacky shenanigans! First he took all the best buffalo wings and left me with the smallest ones for leftovers, and now this! For SHAME.

Why did I remove the two things I claimed I would not change? Basically, it was out of a fear of commitment, they really aren’t necessary, and they dragged things on. Three panels of this comic were originally devoted simply to Ellen and Grace reacting to the eye patch and scars, and while I could have had them ignore it, I wouldn’t buy it. No matter how open minded and considerate one may be, there’s going to be some sort of reaction to something like that.

As for the commitment, if such aspects of a character is introduced and given panel time, it’s basically a promise to address those aspects in detail later on. How and why was he injured, what is the significance to his character, etc. The principal may or may not be given adequate attention down the line to justify such things. Even if I plan to now, I could change my mind later, and my reasoning for having such traits could be accomplished in other ways that wouldn’t require such commitment.

Basically, it boils down to Chekhov’s gun. The eye patch and the scarring were unnecessary, and therefore not introduced.